Gotta love my 2.5kg W520. Once I get the spare dosh to replace the ram and maybe HD, it'll be good for another 4 years, and I got it secondhand in pristine condition. My old X60, which was second hand, got used 3-4 years, and got resold, yet again! These machines aren't beasts, they're leviathans before which apples cower to their core, shedding their to-some-shiny, -seductive red skin.
It has been shown that longer lives occur in many species, from yeasts and c.elegans, to primates. Pubmed fetches lots of articles (arguing for both sides) given a search like 'caloric restriction aging'